Project Summary/Abstract Background. Exercise is generally considered a non-pharmacological strategy that plays an important protective role in preserving cognitive function or mitigating the progression of cognitive impairment for older adults with mild cognitive impairment (MCI). Most exercise interventions, however, focus exclusively on physical development. Relatively few interventions have either combined physical and cognitive training concomitantly or explicitly integrated cognitive-physical components for cognitive stimulation. Moreover, the evidence that exercise improves cognitive function in older adults with MCI is both limited and inconclusive, making it difficult to recommend best practices. Objective. The primary objective of this application is to determine the efficacy of a cognitively enhanced exercise intervention - Tai Ji Quan: Moving to Maintain Brain Health (TJQMMBH). TJQMMBH is built on a comprehensively researched, evidence-based program that has been shown to have multiple health outcomes but now explicitly integrates a cognitive component aimed at increasing multitasking costs and cognitive demands on performing deliberate daily motor tasks. Accordingly, grounded on our promising pilot data, our primary aim in this proposed study is to determine whether the newly developed TJQMMBH intervention will have a positive effect on cognitive function in older adults with amnestic MCI. We also have four secondary aims that will examine whether (1) TJQMMBH can slow the progression of cognitive impairment; (2) improvement in global cognitive function is mediated through gains in movement confidence; (3) the benefits of the TJQMMBH intervention on cognitive outcomes persist over a post-intervention follow-up period; and (4) there is an association between change in executive function and physical performance. Approach. Our core approach to achieving our research aims is to perform a prospective, single-blind, 3-arm, randomized (active control) trial in which the cognitively enhanced TJQMMBH intervention will be evaluated against a standard Tai Ji Quan intervention and a stretching exercise control. Our design will allow us to test the hypothesis regarding the efficacy of a 6-month TJQMMBH intervention, relative to standard Tai Ji Quan and stretching control, in improving the primary outcomes of global cognitive function and motor-cognitive dual- task gait performance and the secondary outcomes of domain-specific cognitive functions in community- dwelling older adults who have been diagnosed with amnestic MCI per established clinical criteria. Significance and impact. This work is significant because it addresses the currently limited options in community and clinical practice for offering the most effective strategies that address cognitive decline in older adults with MCI. Therefore, if the proposed intervention proves to be effective, the scientific impact is likely to be high in terms of providing an alternative, non-pharmacological-based cognitive training intervention to ameliorate cognitive decline in older Americans with MCI and delay or prevent the onset of dementia.